There's a friend of mine who has been asking if I could get him onto my haunt's crew this year. I had to tell him no, because they require the workers to be at least 16 years old to work there. I just wondered what your opinion on age restrictions for workers were.

We run a volunteer haunt and do not accept kids until they are of 8th grade age. Now granted, we have removed some of these 8th graders or at least delegated them to dead ends, but also we have accepted in-the-family elementary school students. Always handy to have a few little kids around to stick in scenes, and honestly some can scare better than adults!

What could possibly go real wrong in the dark where people are trying to scare or become scared? What happens when two bodies collide? The smaller, younger body usually gets most of the abuse from this happening, if you don't think so watch a pick-up basketball game , watch when the tall rebounder's elbows come down on top of the short kid's head!
When a psycho or drunk needs to swing a punch at someone, they will almost always swing at the smaller, shorter of the two people standing there. (They might be somewhat drunk , but some part of their brain still reguards their own physical survival highly.) If a mask is too big to allow the eye holes to line up the kid in the mask won't see the punch coming, could this ever happen?
Kids are kids and their youthful enthusiasm can make them ignore of forget any common sense or previous instructions some times. There are a few things that someone scaring should not do, for their safety and the wellbeing of the customers. Never get closer to a potential "Victim" than arm's length, their arm, that punch/dispensing part of human anatomy.
If they come at you, quickly back away, if they continue coming at you shine a bright flashlight into their eyes and make good your escape, call for security. (Putting anyone, especially a physically smaller kid in a dead end should never happen.)
If the haunt is run by kids for kids with parental/adult supervision, forget most of what I have typed here.